Difference between revisions of "Net Force"
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| − | ===12. | + | ===12. A rocket has engines that produce 60. N of thrust. What is its mass if it accelerates upward at 40. m/s/s?=== |
<blockquote> | <blockquote> | ||
| − | + | Here comes a whole bunch of Algebra...<br><br> | |
| + | F = ma<br><br> | ||
| + | (60 N - (mg)) = m(40 m/s<sup>2</sup>)<br><br> | ||
| + | 1.5 N/m/s<sup>2</sup> - mg / 40 m/s<sup>2</sup> = m<br><br> | ||
| + | 1.5 N/m/s<sup>2</sup> = mg / 40 m/s<sup>2</sup> + m<br><br> | ||
| + | 1.5 N/m/s<sup>2</sup> = mg + 40m / 40 m/s<sup>2</sup><br><br> | ||
| + | 60 N = 40m + 9.81m<br><br> | ||
| + | 60 N = 49.81m <br><br> | ||
| + | m = 1.2 kg | ||
</blockquote> | </blockquote> | ||
[[#top | Table of Contents]] | [[#top | Table of Contents]] | ||
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===13. Question=== | ===13. Question=== | ||
<blockquote> | <blockquote> | ||
Revision as of 15:57, 20 January 2009
Main Page > Giancoli Physics (5th ed) Solutions > Blank Problem Template
Contents
- 1 About this page
- 2 Problems
- 2.1 1. What is the weight of a 3.4 kg mass?
- 2.2 2. What mass has a weight of 720. N?
- 2.3 3. Bob must exert 240. N of force on a 980. Kg car to move it at a constant speed up an incline. (The frictional and gravity force is 240. N) What is the acceleration of the car if he exerts a force of 350. N?
- 2.4 4. What is the acceleration of a 6.0 Kg object hanging on a string that is under a tension of 80. N? 30. N? (Make up positive)
- 2.5 5. . What force is needed to accelerate a 60.0 Kg cart and rider from rest to 4.20 m/s in 2.50 seconds when the friction force is 24.0 N?
- 2.6 6. What is the mass of a box that moves at a constant velocity along a surface with a force of 15 N, and accelerates at +4.2 m/s/s when you exert +26 N? (The box is moving in the same direction as the forces)
- 2.7 7. If you exert a force of 60. N on a car, it moves at a constant velocity. (i.e. there is a frictional force of 60. N) What is its mass if when you exert 80. N on it, it accelerates from rest to 2.0 m/s in 100. seconds?
- 2.8 8. A 60.0 Kg rocket accelerates upward from rest reaching a height of 23.4 m in 3.00 seconds. What must be the thrust of the engine?
- 2.9 9. It takes 45 N to make a 10. kg cart move at a constant speed. What force does it take to make the cart accelerate at 3.2 m/s/s in the direction it is moving?
- 2.10 10. What tension would accelerate a 5.0 Kg object suspended on a string upwards at 6.2 m/s/s? Downwards?
- 2.11 11. A 45.00 gram rocket accelerates upward from 0 to 12.00 m/s in .05000 seconds. What must be the thrust of the engines?
- 2.12 12. A rocket has engines that produce 60. N of thrust. What is its mass if it accelerates upward at 40. m/s/s?
- 2.13 13. Question
- 2.14 14. Question
- 2.15 15. Question
About this page
All images uploaded for this page must start with the string "Gp5_chapter#_" so the image 16-38.jpg associated with chapter 16 should be uploaded as Gp5_16_16-38.jpg. This way we can avoid conflicts in the image directory, and we can find images easily.
Table of Contents
Problems
1. What is the weight of a 3.4 kg mass?
F = ma
Weight = force
F = 3.4 x 9.8 = 33.32 N
2. What mass has a weight of 720. N?
F = ma
F/a = m
720 N/9.81 m/s = 73.4 m/s
3. Bob must exert 240. N of force on a 980. Kg car to move it at a constant speed up an incline. (The frictional and gravity force is 240. N) What is the acceleration of the car if he exerts a force of 350. N?
F = ma
F/m = a
(350 N - 240 N)/980 kg = .112 m/s2
4. What is the acceleration of a 6.0 Kg object hanging on a string that is under a tension of 80. N? 30. N? (Make up positive)
F = ma
6 kg * 9.81 m/s = 58.9 N
A. (80 N - 58.9 N) = (6 kg)a
21.1 N = (6 kg)a
a = 3.5 m/s2
B. (30 N - 58.9 N) = (6 kg)a
(-28.9 N) = (6 kg)a
a = -4.8 m/s2
5. . What force is needed to accelerate a 60.0 Kg cart and rider from rest to 4.20 m/s in 2.50 seconds when the friction force is 24.0 N?
v/t = a
(4.2 m/s)/(2.5 s) = 1.68 m/s2
F = ma
(F - 24 N) = (60 kg)(1.68 m/s2)
F = 125 N
6. What is the mass of a box that moves at a constant velocity along a surface with a force of 15 N, and accelerates at +4.2 m/s/s when you exert +26 N? (The box is moving in the same direction as the forces)
F = ma
(26 N - 15 N) = m(4.2 m/s2)
m = 2.6 kg
7. If you exert a force of 60. N on a car, it moves at a constant velocity. (i.e. there is a frictional force of 60. N) What is its mass if when you exert 80. N on it, it accelerates from rest to 2.0 m/s in 100. seconds?
F = ma
(2.0 m/s) / (100 s) = .02 m/s2
(80 kg - 60 kg) = m(.02 m/s2)
m = 1000 kg
8. A 60.0 Kg rocket accelerates upward from rest reaching a height of 23.4 m in 3.00 seconds. What must be the thrust of the engine?
SUVAT!!!
s = ut + .5at2
23.4 = .5a(3)2
a = 5.2 m/s2
F = ma
(F - (9.81m/s2 * 60 kg)) = 60 kg * 5.2 m/s2
F = 901 N
9. It takes 45 N to make a 10. kg cart move at a constant speed. What force does it take to make the cart accelerate at 3.2 m/s/s in the direction it is moving?
F = ma
(F - 45 N) = 10 kg * 3.2 m/s2
F = 77 N
10. What tension would accelerate a 5.0 Kg object suspended on a string upwards at 6.2 m/s/s? Downwards?
F = ma
A. (F - (5 kg * 9.81 m/s2) = 5 kg * 6.2 m/s2
F = 80 N
B. (F - (5 kg * 9.81 m/s2) = 5 kg * -6.2 m/s2
F = 18 N
11. A 45.00 gram rocket accelerates upward from 0 to 12.00 m/s in .05000 seconds. What must be the thrust of the engines?
SUVAT!!! AGAIN!!!
v = u + at
12 m/s = 0 m/s + a(.05 s)
a = 240 m/s2
F = ma
(F - (.045 kg * 9.81 m/s2)) = .045 kg * 240 m/s2
F = 11.24 N
12. A rocket has engines that produce 60. N of thrust. What is its mass if it accelerates upward at 40. m/s/s?
Here comes a whole bunch of Algebra...
F = ma
(60 N - (mg)) = m(40 m/s2)
1.5 N/m/s2 - mg / 40 m/s2 = m
1.5 N/m/s2 = mg / 40 m/s2 + m
1.5 N/m/s2 = mg + 40m / 40 m/s2
60 N = 40m + 9.81m
60 N = 49.81m
m = 1.2 kg
13. Question
Solution goes here
14. Question
Solution goes here
15. Question
Solution goes here
